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Abstract

"Olivine, pyroxene,and spinel were crystallized in the ternary system anorthite-forsterite-silica to which trace amounts of the transition metal ions Cr³⁺, Fe²⁺, Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺ had been added. The resulting concentrations of the transition metal ions in the liquid and crystalline phases were determined using the electron microprobe. The results, given as free energies and partition functions, indicate the order of substitution of the dipositive ions in all crystals to be Ni²⁺, Co²⁺, Mn²⁺, Cu²⁺, and Fe²⁺ according to the predictions of crystal field theory. The ion Cr³⁺ substituted in greater or lesser quantities depending on the crystalline phase. The data at different temperatures permitted the calculation of the entropy function for each element. The results demonstrate that the higher concentrations of trace elements in crystals at lower temperatures are largely due to the entropy function, i.e. ΔS is negative. The modification of the crystallization paths of this system by the small amounts of trace elements indicates the need for further study in this area"--Abstract, page ii.